Miniaturized products have become increasingly dominant in the medical field. The benefits of having smaller components include ease of movement, reduced packaging and shipping costs, reduced power consumption, and fewer problems with thermal distortion and vibration. In light of these advantages, miniaturization of systems and devices has become an active area of research. In the past decade, enormous progress has been made in developing new fabrication techniques and materials for developing smaller biomedical devices. One promising area of research that could provide for substantial miniaturization of devices involves the use of carbon nanotubes.
Carbon nanotubes exhibit impressive structural, mechanical, and electronic properties in a small package, including higher strength and higher electrical and thermal conductivity. Carbon nanotubes are essentially hexagonal networks of carbon atoms and can be thought of as a layer of graphite rolled up into a cylindrical shape.
Techniques being used for producing carbon nanotubes include 1) a carbon arc-discharge technique, 2) a laser-ablation technique, 3) a chemical vapor deposition (CVD) technique, and 4) a high pressure carbon monoxide technique.
Before the advent of carbon nanotubes, the traditional method of generating x-rays comprised the use of a metallic filament (cathode) that acts as a source of electrons when heated to a very high temperature. Electrons emitted from the heated filament are then bombarded against a metal target (anode) to generate x-rays.
Research has reported, however, that field emission may be a better mechanism of extracting electrons compared to thermoionic emission. In field emission, the electrons are emitted at room temperature and the output current is voltage controllable. In addition, the voltage necessary for electron emission is lowered.